Initiators for materials which can be polymerized cationically

ABSTRACT

Initiator compositions for materials which can be polymerized cationically are described, these containing 
     i) an anhydride of a polycarboxylic acid, a polyisocyanate, a cyclic carbonate, a lactone or a mixture of such compounds, and dissolved therein 
     ii) at least one compound of the formula I 
     
         [M.sup.+n (L).sub.x ].sup.n+ n X.sup.-                     (I) 
    
     in which n is 2 or 3, M is a metal cation selected from the group consisting of Zn 2+ , Mg 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cr 2+ , Ru 2+ , Mn 2+ , Sn 2+ , VO 2+ , Fe 3+ , Al 3+  and Co 3+ , X -  is an anion which is selected from the group consisting of AsF 6   - , SbF 6   - , BiF 6   -  and derivatives derived from these anions in which a fluorine atom is replaced by hydroxyl groups, or in which up to 50% of the anions X - , based on the total amount of anions, can also be any desired anions, L is water or an organic σ-donor ligand which contains, as ligand sites, one or more functional radicals selected from the group consisting of --CO--, --CO--O--, --O--CO--O--and --O--, and which forms σ-bonds with the central atom via the oxygen atom or via the oxygen atoms, and x is an integer from 0 to 6, it being possible for the ligands L to differ within the context of the definitions given.

This is a divisional of Ser. No. 874,782 filed Apr. 27, 1992 now U.S.Pat. No. 5,179,179, which is a divisional of Ser. No. 496,557 filed Mar.19, 1990 now U.S. Pat. No. 5,130,406.

The present invention relates to novel initiator compositions formaterial which can be polymerized cationically, selected novel metalcomplexes, processes for the preparation of the initiator compositionsand the metal complexes, materials which can be polymerized cationicallyand contain these initiator compositions, a process for the preparationof hardened products using the novel initiator compositions and thehardened products.

Hardenable compositions which contain materials which can be polymerizedcationically, preferably epoxy resins, and metallocene salts ashardening agents are described in EP-A-94,915 and -109,851.

In these compositions which are already known, the organometalliccomplex salts are in general activated by irradiation with actinicradiation after being mixed into the material to be polymerized andbefore hardening by heat, it being possible for partial polymerizationto take place, depending on the material and radiation conditions, andthe compositions are then hardened by means of heat, or the compositionsare hardened directly at high temperatures, as a rule at close to thedecomposition point of the complex salt.

For a number of uses, for example for use in covering processes in theproduction of integrated circuits or as rapidly hardening one-componentadhesives, hardenable compositions are required which combine propertieswhich are in themselves opposite and are therefore difficult to realizewith one another, such as adequate processing stability of thenon-hardened composition (pot life) and the fastest possible rate ofhardening at the lowest possible temperatures.

Epoxy-based encapsulating systems which can be hardened rapidly areknown from EP-A-235,077. These systems contain selected diglycidylethers, hardening catalysts, sterically hindered phenols or phosphitesand certain reactive diluents. A zinc tetrafluoroborate complex whichcontains water and tetrahydrofuran as ligands is described as thehardening catalyst. The concentration of the hardener must in general beadjusted precisely in order to achieve processing stability combinedwith a high rate of hardening.

Initiators for compounds which can be polymerized cationically have nowbeen found, which are employed in combination with a reactive diluent sothat control of the initiator activity is possible. Such initiatorsystems can be processed in a simple manner and moreover lead tocrosslinked products having advantageous final properties.

The high heat stability of the hardened product is to be regarded inparticular as surprising. In addition, the products hardened with theseinitiator compositions are distinguished by a good colour stability andby an unexpectedly firm bonding of the initiator constituents to thehardened resin, and thus by a low degree of corrosion. Ions of theinitiator are thus not washed out of the resin in the "pressure cookertest" (20 g of powdered sample are boiled together with 100 ml ofdeionized water at 121° C./1.2 bar for 20 hours; the electricalconductivity of the water is then determined). Another advantage of theinitiator compositions according to the invention is the highthroughputs which can be achieved, especially during mechanicalprocessing, since rapid gelling is possible at low temperatures and alsosince the after-hardening times at a higher temperature can be cutshort. The initiator action is furthermore retained after the hardeningprocess is interrupted, so that the hardening reaction starts up againon renewed heating up. The fact that the mixing ratio of the resin andhardener components is in general not critical for the hardeningconditions is to be regarded as a further advantage during processing ofthe hardenable compositions according to the invention. This mixingratio can thus be varied, especially during mechanical processing,without the hardening conditions having to be adjusted each time.

Activation of the hardenable compositions by irradiation before thehardening step can furthermore be dispensed with for the novel initiatorcompositions, so that a simplification during processing generallyresults, especially in systems having a high filler content or in thecase of hardening in thick layers, for which complete irradiation of thetotal hardenable composition may present problems.

The present invention relates to compositions of matter containing

i) an anhydride of a polycarboxylic acid, a polyisocyanate, a cycliccarbonate, a lactone or a mixture of such compounds, and dissolvedtherein

ii) at least one compound of the formula I

    [M.sup.+n (L).sub.x ].sup.n+ n X.sup.-                     (I)

in which n is 2 or 3, M is a metal cation selected from the groupconsisting of Zn²⁺, Mg²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cr²⁺, Ru²⁺, Mn²⁺, Sn²⁺,VO²⁺, Fe³⁺, Al³⁺ and Co³⁺, X⁻ is an anion which is selected from thegroup consisting of AsF₆ ⁻, SbF₆ ⁻, BiF₆ ⁻ and derivatives derived fromthese anions in which a fluorine atom is replaced by hydroxyl groups, orin which up to 50% of the anions X⁻, based on the total amount ofanions, can also be any desired anions, L is water or an organic σ-donorligand which contains, as ligand sites, one or more functional radicalsselected from the group consisting of --CO--, --CO--O--, --O--CO--O--and --O--, and which forms σ-bonds with the central atom via the oxygenatom or via the oxygen atoms, and x is an integer from 0 to 6, it beingpossible for the ligands L to differ within the context of thedefinitions given.

The expression "up to 50% of the anion X⁻ can also be any desiredanions" is to be understood as meaning that in compounds of the formulaI about half the total anions present can have any desired meaning. Thepossible content of anions which differ from AsF₆ ⁻, SbF₆ ⁻, BiF₆ ⁻ orderivatives thereof containing hydroxyl groups depends on the desiredactivity of the initiator compositions. A compound of the formula Icontaining anions which differ from AsF₆ ⁻, SbF₆ ⁻, BiF₆ ⁻ orderivatives thereof containing hydroxyl groups is regarded as usable forthe purposes of the present invention if, in combination with componenti), it is capable of hardening a material which can be polymerizedcationically. This can be determined by the expert by routine studies.

The term "organic σ-donor ligand" is to be understood as meaning that Lis any σ-donor ligand which forms a metal-ligand σ-bond via an oxygenatom of the functional groups defined above. The term "σ-donor ligand"is to be understood here in the broadest sense, as defined, for example,in R. P. Houghton, Metal Complexes In Organic Chemistry, page 4,Cambridge University Press, 1979. The systems here can thus be pureσ-donors, σ- and π-donors or σ-donors and π-acceptors.

The size of the index x describes the number of ligands L. This numberin general depends on the extent to which the central atom M^(+n) issaturated by coordination and on how many ligand sites a particularligand has. For the purposes of the present invention, compounds of theformula I in which the central atom is not saturated, partly saturatedor completely saturated by coordination can be employed. The number ofligands L can be between zero and six. In the case where the compound ofthe formula I contains ligands L and the central atom is saturated bycoordination, x assumes a value, depending on the number of ligand sitesin L, such that the central atom is complexed with eight or inparticular with six oxygen atoms of the ligand sites of the ligand orligands L. In the case of selected ligands, more than eight oxygen atomscan also complex the central atom. Thus if L is a monodentate ligand, xis in general six, in the case of bidentate ligands x is in generalthree, in the case of tridentate ligands x is in general two and in thecase of tetradentate or more highly dentate ligands x is in general oneor two.

Examples of possible ligand types L are alcohols, including phenols,water, ethers, aldehydes, ketones, ketenes, acetals, acylals, acyloins,carboxylic acids or functional derivatives of carboxylic acids, forexample esters or anhydrides thereof, including lactones and cycliccarbonates, and hydroxycarboxylic acids and oxocarboxylic acids andesters and anhydrides thereof.

Of these ligands, water, ethers, ketones, carboxylic acid anhydrides andcarboxylic acid esters, in particular the lactones and anhydrides ofdicarboxylic acids, are particularly preferred.

The carboxylic acid, anhydride or ester ligands L are quite generallyaliphatic, cycloaliphatic, aromatic or araliphatic compounds having oneor more than one carboxyl group in the molecule.

The preferred number of carbon atoms is 2 to 40 in the aliphaticcarboxylic acids and 7 to 12 in the cycloaliphatic, aromatic andaraliphatic carboxylic acids.

Examples of compounds having a carboxyl group in the molecule aresaturated and unsaturated aliphatic monocarboxylic acids, such as aceticacid, propionic acid, butyric acid, valeric acid, isovaleric acid,pivalic acid, caproic acid, lauric acid, myristic acid, palmitic acid,stearic acid, arachic acid or acrylic acid, methacrylic acid, propiolicacid, crotonic acid, isocrotonic acid, tetraolic acid, sorbic acid oroleic acid; or cycloaliphatic monocarboxylic acids, such ascyclohexanecarboxylic acid; or aromatic monocarboxylic acids, such asbenzoic acid, naphthoic acids or tolylic acids; or araliphaticmonocarboxylic acids, such as hydrotropic acid, atropic acid or cinnamicacid.

Examples of compounds containing more than one carboxyl group in themolecule are saturated aliphatic dicarboxylic acids, such as oxalicacid, malonic acid, succinic acid, α-methylsuccinic acid, glutaric acid,adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid ordimerized linoleic acid; or unsaturated aliphatic dicarboxylic acids,such as maleic acid, fumaric acid, mesaconic acid, citraconic acid,glutaconic acid or itaconic acid; or cycloaliphatic dicarboxylic acids,such as camphoric acid, hexahydrophthalic, hexahydroisophthalic orhexahydroterephthalic acid, tetrahydrophthalic, tetrahydroisophthalic ortetrahydroterephthalic acid or 4-methyltetrahydrophthalic acid,4-methylhexahydrophthalic acid or endomethylenetetrahydrophthalic acid;or aromatic dicarboxylic acids, such as phthalic, isophthalic orterephthalic acid; or tricarboxylic and higher carboxylic acids, such asaromatic tri- or tetracarboxylic acids, for example trimellitic acid,trimesic acid, pyromellitic or benzophenonetetracarboxylic acid.

The anhydrides as a rule have one or two anhydride groups in themolecule. They can be intramolecular anhydrides or intermolecularanhydrides. The intermolecular anhydrides can be anhydrides of the sameor different carboxylic acids. Examples of such ligands are theanhydrides of the carboxylic acids listed above.

If L is an ester, this is in general derived from an aliphatic,cycloaliphatic, aromatic or araliphatic mono- or polycarboxylic acid,which as a rule is esterified with a monohydric aliphatic,cycloaliphatic, aromatic or araliphatic alcohol.

Suitable mono- or polycarboxylic acids for the preparation of theseesters are listed above.

Examples of alcohols which can be employed as ligands L or for theesterification are monohydric aliphatic alcohols having 1 to 20 carbonatoms, such as methanol, ethanol, n-propanol, isopropanol, butanol,pentanol, hexanol, octanol, decanol, dodecanol, tetradecanol,hexadecanol, octadecanol or eicosanol, monohydric cycloaliphaticalcohols having 5 to 12 carbon atoms, such as cyclopentanol orcyclohexanol, or monohydric phenols having 6 to 14 carbon atoms, such asphenol, cresols or naphthols.

The esters also include, in particular, lactones, especially lactones ofaliphatic hydroxycarboxylic acids, such as γ-butyrolactone,γ-valerolactone, δ-valerolactone, ε-caprolactone or crotonolactone, orcyclic carbonates. If L is a cyclic carbonate, this is in generalunderstood as meaning an aliphatic compound having a carbonate group.The preferred number of carbon atoms is 5 to 12. An example of suchligands L is γ-propylene carbonate.

If L is an ether, this is in general derived from a mono- to tetrahydricaliphatic, cycloaliphatic, aromatic or araliphatic alcohol. Such etherscan contain free hydroxyl groups. The ether group can be part of acarbon chain or is part of a ring system.

Ligands L having ether groups as part of a carbon chain are derived, forexample, from monohydric alcohols. Such alcohols are listed above, forexample, as esterification components of the ester ligands L.

Examples of ligands L having ether groups as part of a carbon chainbased on polyhydric alcohols are the polyalkyl ethers, in particular thedi-, tri- or tetramethyl, -ethyl, -propyl or -butyl ethers, of aliphaticdi-, tri- or tetraols, such as ethylene glycol, diethylene glycol andhigher poly-(oxyethylene) glycols, propane-1,2-diol, propane-1,3-diol orhigher poly-(oxypropylene) glycols, butane-1,4-diol or higherpoly-(oxybutylene) glycols, pentane-1,5-diol, neopentylglycol(2,2-dimethylpropanediol), hexane-1,6-diol, octane-1,8-diol,decane-1,10-diol, dodecane-1,12-diol, hexane-2,4,6-triol, glycerol,1,1,1-trimethylolethane, 1,1,1-trimethylolpropane or pentaerythritol; orthe dimethyl, -ethyl, -propyl or -butyl ethers of cycloaliphatic diols,such as 1,3- or 1,4-dihydroxycyclohexane, 1,4-cyclohexanedimethanol,bis-(4-hydroxycyclohexyl)-methane, 2,2-bis-(4-hydroxycyclohexyl)-propaneor 1,1-bis-(hydroxymethyl)-cyclohex-3-ene; or the di-, tri- ortetramethyl, -ethyl, -propyl or -butyl ethers of di-, tri- ortetraphenols or mono- or polynuclear polyphenols, such as resorcinol,hydroquinone, bis-(4-hydroxyphenyl)-methane,2,2-bis-(4-hydroxyphenyl)-propane, bis-(4-hydroxyphenyl) ether,bis-(4-hydroxyphenyl) sulfone, 1,3,5-trihydroxybenzene or1,1,2,2-tetrakis-(4-hydroxyphenyl)-ethane. These polyhydric alcohols orphenols can also themselves be employed as ligands L.

Ligands L having ether groups as part of a ring system are derived frompolyhydric alcohols, in particular from diols. Examples of such ligandsare tetrahydrofuran, dioxane or crown ethers, such as 18-crown-6,15-crown-5 or 12-crown-4.

Preferred ether ligands contain two or in particular one ether group inthe molecule. Cyclic ether ligands are particularly preferred.

If L is an aldehyde, the compound is an aliphatic, cycloaliphatic,aromatic or araliphatic compound having preferably one or two aldehydegroups in the molecule. Examples of these are aldehydes of thecarboxylic acids listed above.

If L is a ketone, the compound is an aliphatic, cycloaliphatic, aromaticor araliphatic compound having preferably one or two keto groups in themolecule. The ketone group can be part of a carbon chain or is part of aring system. The term "ketone" also includes quinones.

Examples of aliphatic ketones are acetone, methyl ethyl ketone, ethylpropyl ketone, diisopropyl ketone and hexane-2,4-dione.

Examples of cycloaliphatic ketones are 1,4-benzoquinone, cyclopentanoneor cyclohexanone.

Examples of aromatic ketones are 1,4-naphthoquinone, anthraquinone orbenzophenone.

Examples of araliphatic ketones are acetophenone, propiophenone,chalcone or desoxybenzoin.

Ligands L which have several different ligand sites in one molecule arealso possible. An example of this is 2-methoxyethanol.

If some of the anions X⁻ in a compound of the formula I have any desiredmeaning, these can be, for example, sulfate, phosphate, halide,carboxylate or sulfonate anions. They are preferably chloride orfluoride.

Preferred components ii) include compounds of the formula II

    [(L.sup.1).sub.a M.sup.+n (L.sup.2).sub.b ].sup.n+ n X.sup.-(II)

in which M, X and n are as defined above, L¹ is a mono- to tetradentateσ-donor ligand and is an aliphatic, cycloaliphatic, aromatic oraraliphatic compound having one or two ketone, anhydride, carbonate orester groups or one to six ether groups per molecule, it being possiblefor the ligands L¹ of a compound of the formula II to differ in thecontext of the definitions given, L² is water, b is an integer from 0 to2, preferably 0, and, if L¹ is a monodentate ligand, a is an integerfrom 4 to 6 and the sum of a and b is in each case 6, and if L¹ is abidentate ligand, a is an integer from 2 to 3 and the sum of 2a and b isin each case 6, and if L¹ is a tridentate ligand, a is 1 or 2 and thesum of 3a and b is 6, and if L¹ is a tetra-, penta- or hexadentateligand, a is 1 and the sum of 4a and b or of 5a and b or of 6a and b is6 or 8.

Component i) of the initiator compositions according to the invention isan anhydride of a polycarboxylic acid, a polyisocyanate, a cycliccarbonate or a lactone. Examples of anhydrides of a polycarboxylic acid,cyclic carbonates or lactones are listed above as possible ligands L.

If component i) is a polyisocyanate, in general any aliphatic,cycloaliphatic, aromatic or araliphatic compound having at least twoisocyanate groups or isocyanate groups which are blocked and can bedeblocked by heating, and in which component ii) can be dissolved, canbe used.

Preferred polyisocyanates contain three or in particular two isocyanategroups and have 6 to 20 carbon atoms. Aromatic diisocyanates, inparticular 4,4'-diisocyanatodiphenylmethane and industrial mixtures ofdifferent diisocyanatodiphenylmethanes, are especially preferred.

Polyisocyanates are particularly preferred as components i) sincehardened products having particularly high glass transistiontemperatures can as a rule be prepared with such initiator compositions.

Examples of preferred polyisocyanates are 2,4-diisocyanatotoluene andindustrial mixtures thereof with 2,6-diisocyanatotoluene,2,6-diisocyanatotoluene, 1,5-diisocyanatonaphthalene,4,4'-diisocyanatodiphenylmethane and industrial mixtures of variousdiisocyanatodiphenylmethanes (for example the 4,4'- and 2,4'-isomers),urethanized 4,4'-diisocyanatodiphenylmethane, carbodiimidized4,4'-diisocyanatodiphenylmethane, the uretdione of2,4-diisocyanatotoluene, triisocyanatotriphenylmethane, the adduct ofdiisocyanatotoluene and trimethylolpropane, the trimer oftriisocyanatotoluene, diisocyanato-m-xylylene andN,N'-di-(4-methyl-3-isocyanatophenyl)-urea, mixed trimerization productsof diisocyanatotoluene and 1,6-diisocyanatohexamethylene,1,6-diisocyanatohexane, 3,5,5-trimethyl-1-isocyanatomethylcyclohexane(isophorone diisocyanate), N,N',N"-tri-(6-isocyanatohexyl)-biuret,2,2,4-trimethyl-1,6-diisocyanatohexane,1-methyl-2,4-diisocyanatocyclohexane, dimeryl diisocyanate,4,4'-diisocyanatodicyclohexylmethane, trimeric isophorone diisocyanate,trimeric hexane diisocyanate and methyl 2,6-diisocyanatohexanoate.

Preferred components i) are anhydrides of polycarboxylic acids, inparticular those anhydrides which are known per se as epoxy hardeners.Anhydrides of dicarboxylic acids are particularly preferably used.Examples of such preferred components i) are tetrahydrophthalicanhydride, methyl-tetrahydrophthalic anhydride, hexahydrophthalicanhydride and in particular methyl-hexahydrophthalic anhydride.

The amount of compound of the formula I is in general chosen so that, incombination with a hardenable material, a processing stability and rateof hardening which are adequate for the particular intended use result.The amount required in an individual case can be determined by simpleexperiments. The amount of component ii) in general varies between 0.05and 10% by weight, based on the total weight of components i) and ii).

With the exception of bis-{[12]-crown-4}-iron(II) hexafluoroantimonate,bis-{[15]-crown-5}-iron(II) hexafluoroantimonate and([12]-crown-4)([15]-crown-5)-iron(II) hexafluoroantimonate, thecompounds of the formula II are novel and the present invention likewiserelates to these.

The compounds which are already known are described in Angew. Chem., 97(10), pages 879-80 (1985). No intended use of these compounds is stated.

The index n is preferably 2.

Initiator compositions of compounds of the formula II in which b is 0 orthese compounds are preferred.

Initiator compositions of compounds of the formula II in which a is 6 or3 or these compounds are preferred.

M is preferably a metal cation selected from the group consisting ofFe²⁺, Zn²⁺, Mg²⁺, Co²⁺, Mn²⁺, Sn²⁺ and Al³⁺.

M especially preferably is a metal cation selected from the groupconsisting of Zn²⁺, Mn²⁺, Sn²⁺, Al³⁺ and in particular Fe²⁺.

Compounds of the formula I or II in which all the anions X⁻ are selectedfrom the group consisting of AsF₆ ⁻, SbF₆ ⁻, SbF₅ (OH)⁻ and BiF₆ ⁻ arepreferably used for the preparation of the initiator compositionsaccording to the invention. The preferred anion X⁻ is SbF₆ ⁻.

Preferred initiator compositions are liquid at temperatures below 50°C., in particular below 30° C., in order to facilitate incorporationinto the material which can be polymerized cationically.

Particularly preferred initiator compositions contain as component i)anhydrides of polycarboxylic acids, in particular dianhydrides ofpolycarboxylic acids.

Although the composition of the initiator compositions according to theinvention is not known specifically, it is assumed that on dissolving incomponent i) the ligand L in component ii) is replaced by this componentpresent in excess, in particular by anhydride ligands.

The anhydride complexes of the formula I are particularly preferred, andthe compounds of the formula II in which a is 6 or 3, b is 0 and L¹ isan aliphatic, cycloaliphatic, aromatic or araliphatic compound havingone or two carboxylic acid anhydride groups are especially preferred.

Compounds which are liquid at temperatures below 50° C., in particularbelow 30° C., are particularly preferred as component i). The componentcan also be liquid mixtures of such compounds.

The compositions according to the invention can be prepared bydissolving compounds of the formula I in a component i) as definedabove.

The compounds of the formula I or II can in general be obtained byvarious processes a) to e).

The compounds of the formula II in which M is Fe²⁺ and b is 0 can beobtained, for example, by process a). For this, a π-complex of theformula III

    [(R.sup.1)Fe.sup.+2 (R.sup.2)].sup.+a aX.sup.-

in which R¹ is a π-arene and R² is an anion of a π-arene, for example acyclopentadienyl anion, or in particular is a π-arene, a is 1 or 2 andX⁻ is as defined above, is dissolved in a ligand L¹ as defined above,which is to be introduced, or in a mixture of these compounds and thesolution is irradiated with actinic radiation or heated until the ligandexchange of R¹ and R² for L¹ has essentially taken place, and theproduct is then separated off from the reaction mixture in a mannerwhich is known per se.

The conversion of the compound of the formula III can be monitored bychromatographic or spectroscopic methods in a manner which is known perse, for example by monitoring the intensity of an absorption bandcharacteristic of the starting complex of the formula III.

The amount of starting substance of the formula III and ligand L¹ to beintroduced are in general chosen so that preferably ten to one hundredmol of the compound L are present per mol of compound of the formulaIII.

The reaction can be carried out by heating, depending on the stabilityof the starting complex. However, the reaction can also be carried outby irradiation of the starting complex of the formula III with actinicradiation, a wavelength at which the starting complex absorbs beingused.

The product of the formula II in general crystallizes out in thereaction mixture during the irradiation or during cooling, or can beprecipitated from the reaction mixture by addition of a non-solvent forthe product. The product is then removed from the mixture by means ofroutine operations, such as filtration or extraction.

The starting compounds of the formula III are known per se and aredescribed, for example, in EP-A-94,915.

For carrying out process b) a metal halide of the formula IV togetherwith an approximately stoichiometric amount of a silver salt of theformula V

    M.sup.+n (HaL).sub.n (IV), AgX                             (V)

in which n, M and X are as defined above and Hal is a halide anion, inparticular chloride or fluoride, are dissolved or suspended in a ligandL¹ as defined above, which is to be introduced, or in a mixture of thesecompounds and if appropriate the reaction mixture is heated, so that theproduct of the formula II is formed.

The amounts of starting substances of the formulae IV and V and ofligand L¹ to be introduced are in general chosen so that about n mol ofthe compound of the formula V and about ten to about one hundred mol ofthe compound L¹ are present per mol of compound of the formula IV.

The reaction is in general carried out at a low temperature, for exampleat 20°-40° C. The product can in this case likewise be separated offfrom the reaction mixture by means of routine operations, for example byfiltering off the silver halide formed and isolating the product formed,as described under process a).

To carry out process c) a metal salt of the formula VI is reacted with acompound of the formula VII ##STR1## in which R₃, R₄ and R₅independently of one another are alkyl, cycloalkyl or aralkyl, inparticular methyl or ethyl, M, n and X⁻ are as defined above and Y⁻ is ahalide anion, alcoholate anion or carboxylic acid anion, together with acompound L¹ as defined above, so that the product of the formula II isformed.

The amount of starting substances of the formulae VI and VII and ofligand L¹ to be introduced are in general chosen so that n mol of thecompound of the formula VII and preferably ten to one hundred mol of thecompound L¹ are present per mol of compound of the formula VI.

The reaction is carried out at room temperature or by heating, forexample in a temperature range from 20°-100° C. The product can in thiscase likewise be separated off from the reaction mixture by means ofroutine operations, for example as described for reaction a).

The compounds of the formula VII are known per se and are described, forexample, in U.S. Pat. No. 3,585,227 or in J. Chem. Soc., Chem.Communications, 1976, pages 33-4.

For carrying out process d), a compound of the formula VIII is reactedwith a Lewis acid of the formula IX

    M.sup.+n F.sub.n (VIII), QF.sub.5                          (IX)

in which n and M are as defined above and Q is As, Sb or Bi. For this,the compound of the formula VIII can be dissolved in an excess of thecompound of the formula IX, or the reaction is carried out in a solventwhich is inert under the reaction conditions and is capable ofdissolving at least one of the compounds of the formula VIII or IX.Examples of suitable solvents are liquid SO₂ or anhydrous HF. Thereaction product in general crystallizes out of the reaction solutionand can be separated off from the mixture by routine processes, such asfiltration.

The resulting product can be employed as such for the preparation of theinitiator compositions according to the invention by dissolving it in acomponent i) as defined above, or the product is dissolved in a ligand Las defined above, which is to be introduced, or in a mixture of theseligands and if appropriate the reaction mixture is heated so that theligand L is introduced into the compound of the formula I. The productcan then be isolated and purified in the same manner as described forprocess a).

Reactions of compounds VIII and IX are described by D. Gantar et al. inJ. Chem. Soc., Dalton Transactions, 1987, pages 2379-83.

The amounts of starting substances of the formulae VIII and IX and ofligand L to be introduced are in general chosen so that n mol of thecompound of the formula IX and preferably ten to one hundred mol of thecompound L are present per mol of compound of the formula VII. Thereaction is carried out at room temperature or by heating, for examplein a temperature range from 20°-200° C.

The variant of process d) for the preparation of the initiatorcompositions according to the invention in which the reaction product ofthe compounds VIII and IX are dissolved directly, after isolationthereof, in component i) is particularly preferred.

According to process e), the compounds of the formula II can also beconverted into other compounds of the formula II by ligand exchange. Forthis, a compound of the formula IIa

    [(L.sup.3).sub.a M.sup.+n (L.sup.2).sub.b ].sup.n+ n X.sup.-(IIa)

in which M, L², X, n, a and b are as defined above and L³ is as definedabove for L¹, is dissolved together with an amount corresponding to atleast the stoichiometry of the desired end product of a ligand L¹ whichdiffers from L³, the solution is heated to carry out the ligand exchangeand the product of the formula II in which all or some of the originalligand L³ is replaced by the newly introduced ligand L¹ is isolated andworked up in the manner described under process a).

The amounts of starting substance of the formula IIa and ligand L¹ to beintroduced are selected according to the stoichiometry of the desiredproduct. For example, if only some of the ligand L³ in the startingsubstance is to be exchanged, less than the stoichiometric amount ofligand L¹ to be introduced is used. This amount also in general dependson the size of the complex formation constant of the product and can bedetermined by the expert by routine processes.

If all the ligands L³ in the starting substance of the formula IIa areto be exchanged, the ligand L¹ to be introduced is as a rule initiallyused in the stoichiometric amount or in a stoichiometric excess. Herealso, the amount of L¹ in general also depends on the size of thecomplex formation constant of the product and is determined by theexpert with the aid of routine processes. About ten to one hundred molof the ligand L¹ are preferably employed per mol of the compound IIa.

The present invention likewise relates to the processes a) to e).

The compounds of the formulae I and II are in general hygroscopic. Thewater-containing compounds of the formulae I and II can be prepared bystorage of the anhydrous compounds of the formula I in air or byreaction of these compounds with water.

The compounds of the formula I having a central atom M which is not oronly partly saturated by coordination can as a rule be obtained from thecompounds saturated by coordination by heating. In this procedure, theligand L is distilled and the compound having the central atom which isnot or only partly complexed is thus obtained.

The compounds of the formula I are distinguished by a high reactivity,and for this reason they are in general used in dilution with acomponent i) as described above. The particular desired reactivity ofthe initiator composition can be established simply and reproducibly byvarying the amount of compounds of the formula I.

The initiator compositions according to the invention can be combinedwith organic materials which can be polymerized cationically to givehardenable compositions having the advantageous properties describedabove. Thus, for example, the very highly reactive compounds of theformula I can be diluted with component i) and the monomer which can bepolymerized cationically to the extent that the content thereof makes uponly 1% of the mixture.

The invention therefore also relates to hardenable compositionscontaining a) an organic material which can be polymerized cationicallyand b) an initiator composition as defined above.

The processing stability of such a hardenable composition can beadjusted, for example, via the amount of initiator composition or thecontent of active component ii) so that a storage stability which isadequate for processing is obtained at low temperatures.

The amount of initiator component b) is as a rule 0.05 to 0.5 part byweight, preferably 0.15-0.3 part by weight per part by weight ofmaterial which can be polymerized cationically.

Components a) and b) are as rule mixed at low temperatures, for examplebelow 50° C., in order to avoid premature gelling or hardening.

Organic materials which can be polymerized cationically and canpreferably be employed are ethylenically unsaturated compounds which canbe polymerized cationically, such as certain mono- or diolefins, orvinyl ethers, for example methyl vinyl ether, isobutyl vinyl ether,trimethylolpropane trivinyl ether, ethylene glycol divinyl ether,3,4-dihydro-2-formyl-2H-pyran and the3,4-dihydro-2-formyl-2H-pyran-2-carboxylic acid ester of2-hydroxymethyl-3,4-dihydro-2H-pyran, or vinyl esters, such as vinylacetate or vinyl stearate, or heterocyclic compounds which can bepolymerized cationically, such as cationically polymerizable cyclicethers or methylol compounds.

Further examples of organic materials which can be polymerizedcationically are described in the abovementioned EP-A-94,915.

Hardenable compositions in which component a) is a cyclic ether whichcan be polymerized cationically are preferred.

The especially preferred components a) include the epoxy resins.

The invention thus particularly relates to hardenable compositionscontaining a compound having on average at least two 1,2-epoxide groupsper molecule, as component a), and component b) as defined above.

A large number of common epoxy resins can be employed as component a).The compounds can be employed by themselves or as a mixture of severalepoxy resins or also in combination with other monomers which can behardened by component b).

Examples of epoxy resins are:

I) Polyglycidyl and poly-(β-methylglycidyl) esters which can beobtained, for example, by reaction of a compound containing at least twocarboxyl groups in the molecule with epichlorohydrin,glycerol-dichlorohydrin or β-methylepichlorohydrin in the presence ofbases.

Examples of compounds having at least two carboxyl groups in themolecule are the polycarboxylic acids, such as have already beendescribed above as components for the preparation of the ester ligand L.

II) Polyglycidyl and poly-(β-methylglycidyl) ethers which can beobtained, for example, by reaction of a compound containing at least twoalcoholic hydroxyl groups and/or phenolic hydroxyl groups in themolecule with epichlorohydrin, glycerol-dichlorohydrin orβ-methylepichlorohydrin under alkaline conditions or in the presence ofan acid catalyst with subsequent treatment with an alkali. Examples ofcompounds having at least two alcoholic hydroxyl groups and/or phenolichydroxyl groups in the molecule are the polyhydric alcohols which havealready been described above as components for the preparation of theether ligand L; or alcohols containing aromatic groups, such asN,N-bis-(2-hydroxyethyl)-aniline; or novolaks, which are obtainable bycondensation of aldehydes, such as formaldehyde, acetaldehyde, chloralor furfuraldehyde, with unsubstituted or alkyl- or halogen-substitutedphenols, such as phenol, the bisphenols described above, 2- or4-methylphenol, 4-tert-butylphenol, p-nonylphenol or 4-chlorophenol.

III) Poly-(S-glycidyl) compounds, such as, for example, di-S-glycidylderivatives which are derived from dithiols, such as ethane-1,2-dithiol,or from bis-(4-mercaptomethylphenyl) ether.

IV) Epoxidation products of dienes or polyenes, such as cycloaliphaticepoxy resins which can be prepared, for example, by epoxidation ofethylenically unsaturated cycloaliphatic compounds. Examples of theseare 1,2-bis-(2,3-epoxycyclopentyloxy)-ethane, 2,3-epoxycyclopentylglycidyl ether, bis-(2,3-epoxycyclopentyl) ether,5(6)-glycidyl-2-(1,2-epoxyethyl)-bicyclo[2.2.1]heptane,dicyclopentadiene dioxide, 3,4-epoxy-6-methylcyclohexylmethyl3',4'-epoxy-6'-methylcyclohexanecarboxylate or 3,4-epoxycyclohexylmethyl3',4'-epoxycyclohexanecarboxylate.

However, epoxy resins in which the 1,2-epoxide groups are bonded todifferent hetero atoms or functional groups can also be used; suchcompounds include, for example, the glycidyl ether glycidyl esters ofsalicylic acid.

The hardenable compositions according to the invention can be obtainedin any desired form, for example as homogeneous liquid or solidmixtures. These compositions can be hardened directly by heat, thehardening temperatures in general being substantially below those of thecompositions already known.

The preferably liquid initiator components can be mixed into thecationically polymerizable organic material by customary means, such aswith stirrers, mills or kneaders, preferably at temperatures below 50°C.

Hardening is preferably carried out below 220° C., in particular in therange from 180° to 200° C. However, preliminary hardening can also becarried out at lower temperatures until the hardenable composition gels,this then being followed by complete hardening at higher temperatures.

The hardened products are distinguished by good mechanical andelectrical end properties, in particular by the advantageous endproperties described above.

The invention thus also relates to a process for the preparation ofhardened products, which comprises hardening a hardenable compositionaccording to the invention by heating; the invention furthermore relatesto the hardened products obtainable by heating the hardenablecompositions according to the invention.

If desired, reactive diluents, for example styrene oxide, butyl glycidylether, 2,2,4-trimethylpentyl glycidyl ether, phenyl glycidyl ether,cresyl glycidyl ether or glycidyl esters of synthetic, highly branched,mainly tertiary aliphatic monocarboxylic acids, can be added to thehardenable compositions to reduce the viscosity.

The compositions according to the invention can furthermore contain, asother customary additives, plasticizers, extenders, fillers andreinforcing agents, for example coal tar, bitumen, textile fibres, glassfibres, asbestos fibres, boron fibres, carbon fibres, mineral silicates,mica, quartz flour, hydrated aluminium oxide, Bentonite®, wollastonite,kaolin, silicic acid aerogel or metal powder, for example aluminiumpowder or iron powder, and furthermore pigments and dyes, such as carbonblack, oxide colours and titanium dioxide, as well as flameproofingagents, foam suppressants, thixotropic agents, flow control agents (someof which are also used as mould release agents), such as silicones,waxes and stearates, or tackifying agents, antioxidants and lightstabilizers.

The amount of additives is usually 0-70 parts by weight per 100 parts byweight of the hardenable composition.

The hardenable compositions according to the invention can be employedquite generally for the preparation of hardened products, and can beemployed in the formulation suitable to the particular specific field ofuse, for example as coating compositions, varnishes, pressingcompositions, dipping resins, casting resins, impregnating resins,laminating resins, adhesives or matrix resins.

The hardenable compositions according to the invention can be employedin particular as a covering material for active and passive electroniccomponents or for the production of insulating materials or shapedarticles.

The invention also relates to the use of the hardenable mixtures for theabovementioned purposes.

The present examples illustrate the invention.

The ¹ H-NMR spectra are measured with a 100 MHz apparatus. The DSC(differential scanning calorimetry) experiments were performed using aMettler TA 3000 DSC apparatus. The heating up rate here is 10°C./minute.

I. Preparation of the compounds of the formula I

I.1. Preparation of hexa-(caprolactone)-iron(II) hexafluoroantimonate[process a)]

80 g (104.2 mmol) of bis-(η⁶ -mesitylene)-iron(II) hexafluoroantimonateare dissolved in 150 ml of caprolactone and the solution is degassedunder argon and exposed to a UV lamp (5000 W dust lamp), while cooling.After an exposure time of 35 minutes, the product is isolated byaddition of 800 ml of dry toluene, filtered off under an inert gas,washed and dried at room temperature under a high vacuum. 118.6 g (97.8mmol=94% of theory) of a white crystalline, very hygroscopic product areobtained.

Elemental analysis for C₃₆ H₆₀ O₁₂ FeSb₂ F₁₂ :

    ______________________________________                                                C      H      Fe        Sb   F                                        ______________________________________                                        Calculated:                                                                             35.67    4.99   4.61    20.09                                                                              18.81;                                 Found:    35.59    4.95   5.00    21.30                                                                              18.55;                                 ______________________________________                                    

IR (KBr): strong band at 660 cm⁻¹ (SbF₆ ⁻); the other main bands in theIR spectrum largely correspond to those of caprolactone;

¹ H-NMR (D₂ O): signals at: 4.36 ppm (2H); 2.67 ppm (2H); and 1.77 ppm;DSC: endothermic decomposition at 240° C.

I.2. Preparation of tris-(ethylene glycol dimethyl ether)-iron(II)hexafluoroantimonate [process a)+e)]

2 g (2.6 mmol) of bis-(η⁶ -mesitylene)-iron(II) hexafluoroantimonate aredissolved in 8 ml of dry acetone and the solution is degassed underargon. The red solution is cooled and exposed to a UV lamp (5000 W dustlamp). After about 5 minutes, the solution is completely decolorized. 5ml of ethylene glycol dimethyl ether are added. The acetone is removedunder a vacuum and the crystals formed are filtered off under an inertgas and washed three times with toluene. After drying under a highvacuum at room temperature, 2.01 g (2.52 mmol=97% of theory) of white,very hygroscopic crystals result.

Elemental analysis for C₁₂ H₃₀ O₆ FeSb₂ F₁₂ :

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated        18.07  3.79;                                                Found:            16.80  3.96;                                                ______________________________________                                    

¹ H-NMR (D₂ O): 3.62 ppm singlet (2H); 3.37 ppm singlet (3H).

I.3. Preparation of bis-(diethylene glycol dimethyl ether)-iron(II)hexafluoroantimonate [process a)+e)]

2.0 g (2.51 mmol=96% of theory) of the abovementioned compound areobtained in a manner analogous to that in Example I.2. by exposure of2.0 g (=2.6 mmol) of bis-(η⁶ -mesitylene)-iron(II) hexafluoroantimonatein dry acetone and subsequent addition of diglyme.

Elemental analysis for C₁₂ H₂₈ O₆ FeSb₂ F₁₂ :

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       18.11  3,55;                                                Found:            18.05  3.87;                                                ______________________________________                                    

¹ H-NMR (D₂ O): 3.38 ppm singlet (3H); 3.66 ppm singlet (4H)

I.4. Preparation of tris-(acetic anhydride)-iron(II)hexafluoroantimonate [process a)]

15 g (19.53 mmol) of bis-(η⁶ -mesitylene)-iron(II) hexafluoroantimonateare dissolved in 30 ml of acetic anhydride and the solution is degassedunder argon. After exposure analogously to Example I.2., the solution iscompletely decolorized after about 20 minutes. After isolation withtoluene, 15.9 g (19.07 mmol=98% of theory) of white, very hygroscopiccrystals result.

Elemental analysis for C₁₂ H₁₈ O₉ FeSb₂ F₁₂ ;

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       17.28  2.17;                                                Found:            16.84  2.45;                                                IR (KBr):         1820, 1800, 1630, 1600,                                                       1140, 1000, 900 and                                                           660 cm.sup.1 ;                                              ______________________________________                                    

¹ H-NMR (D₂ O): 2.2 ppm singlet;

DSC: endothermic peaks at 130° C. (weak) and 220° C. (strong);exothermic decomposition: >270° C.

I.5. Preparation of hexa(acetone)-iron(II) hexafluoroantimonate [processa)]

40 g (52.10 mmol) of bis-(η⁶ -mesitylene)-iron(II) hexafluoroantimonateare dissolved in 120 ml of acetone and the solution is degassed underargon. After exposure analogously to Example I.2., a completelycolourless solution is formed, from which the product crystallizes outafter addition of 400 ml of toluene. After filtration and washing underan inert gas, drying at room temperature under a high vacuum gives 43.5g (49.71 mmol=95% of theory) of colourless, very hygroscopic crystals.

Elemental analysis for C₁₈ H₃₆ O₆ FeSb₂ F₁₂ :

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       24.69  4.14;                                                Found:            23.60  4.07;                                                ______________________________________                                    

¹ H-NMR (D₂ O): 2.22 ppm singlet;

IR (KBr): 3400, 1700, 1380, 1240 and 660 cm⁻¹ ;

DSC: endothermicity 115° C.; exothermicity 173° C.

I.6. Preparation of hexa-(methylhexahydrophthalic anhydride)-iron(II)hexafluoroantimonate [process a)]

6 g (7.81 mmol) of finely powdered bis-(η⁶ -mesitylene)-iron(II)hexafluoroantimonate are dispersed in 30 ml of methylhexahydrophthalicanhydride and partly dissolved. After degassing with argon, the solutionis exposed analogously to Example I.2. until the educt has dissolvedcompletely and the solution is completely decolorized. After addition of100 ml of dry toluene, all the substances are soluble to give a clearsolution. After addition of 200 ml of hexane (dry), the product isprecipitated and the oil formed is separated off under an inert gas andwashed with toluene:hexane (1:2). After drying under a high vacuum atroom temperature, 9.8 g (6.37 mmol=82% of theory) of an amorphousproduct results.

Elemental analysis for C₅₄ H₇₂ O₁₈ FeSb₂ F₁₂ ;

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       42.21  4.72;                                                Found:            41.9   4.84;                                                ______________________________________                                    

IR (KBr): strong band in the IR spectrum at 660 m⁻¹ ; the main bands inthe IR spectrum correspond to those of methyl hexahydrophthalicanhydride.

I.7. Preparation of hexa-(hexahydrophthalic anhydride)-iron(II)hexafluoroantimonate

[process a)]

6 g (7.81 mmol) of bis-(η⁶ -mesitylene)-iron(II) hexafluoroantimonateare dissolved in 25 g of hexahydrophthalic anhydride at 45° C. and thesolution is degassed under argon. The red solution is exposedanalogously to Example I.2. until completely bleached. After addition of50 ml of dry toluene, a clear solution is formed, from which an oilseparates out by addition of 100 ml of hexane. After decanting off,washing under an inert gas and drying at room temperature under a highvacuum, 10.9 g (7.5 mmol=96% of theory) of an amorphous solid productwhich is hygroscopic result.

Elemental analysis for C₄₈ H₆₀ O₁₈ FeSb₂ F₁₂ :

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       39.69  4.16;                                                Found:            39.58  4.60;                                                ______________________________________                                    

¹ H-NMR (CDCl₃): 3.59 ppm (2H); 2.70 ppm (4H); 2.17 and 1.90 ppm (4H);

IR (KBr): band at 660 cm⁻¹ ; the main bands in the IR spectrum corresondto those of hexahydrophthalic anhydride.

I.8. Preparation of hexa-(maleic anhydride)-iron(II)hexafluoroantimonate [process a)] 3.25 g (4.23 mmol) of bis-(η⁶-mesitylene)-iron(II) hexafluoroantimonate are dissolved with 6.95 g ofmaleic anhydride by melting the anhydride and the solution is degassedwith argon and exposed for 30 minutes analogously to Example I.2. Thesolution does not become completely bleached. The product formed isyellowish. After addition of toluene (30 ml), a yellow crystallineproduct forms, which is filtered under an inert gas and washed. Dryingunder a high vacuum at room temperature gives 4.7 g (4.21 mmol=99% oftheory) of yellow, very hygroscopic crystals, which deliquesce anddecolorize in air.

Elemental analysis for C₂₄ H₁₂ O₁₈ FeSb₂ F₁₂ :

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       25.83  1.08                                                 Found:            24.2   2.0;                                                 ______________________________________                                    

¹ H-NMR (D₂ O): singlet at 6.44 ppm;

IR (KBr): band at 660 cm⁻¹, the other bands largely correspond to thoseof maleic anhydride;

DSC: endothermic peak at 115° C. (weak) and 255° C. (strong).

I.9. Preparation of hexa-(tetrahydrofuran)-iron(II) hexafluoroantimonate[process a)].

10 g (20.97 mmol) of (η⁶ -cumene)(η⁵ -cyclopentadienyl)-iron(II)hexafluoroantimonate are dissolved in 70 ml of tetrahydrofuran (dry) andthe solution is degassed under argon. The yellow solution is thenexposed for 30 minutes analogously to Example I.2. The productcrystallizes out and is filtered off under an inert gas, washed threetimes with THF and dried under a high vacuum at room temperature. 9.25 g(9.636 mmol=92% of theory) of a very hygroscopic, white crystallineproduct which rapidly exchanges THF for water in air are obtained.

Elemental analysis C₂₄ H₄₈ O₆ FeSb₂ F₁₂

    ______________________________________                                                C      H      Fe        Sb   F                                        ______________________________________                                        Calculated:                                                                             30.02    5.04   5.82    25.37                                                                              23.75;                                 Found:    28.96    4.89   5.1     25.7 22.8;                                  ______________________________________                                    

¹ H-NMR (d₄ -acetic acid); 2.32 ppm (singlet, 2H); 4.66 ppm (singlet,2H);

IR (KBr): bands at 3400, 2950, 2880, 1460, 1040, 1020, 900 and 660cm^(-1;)

DSC: endothermic peak at 165° C.; exothermic decomposition at 190° C.

I.10. Preparation of hexa-(dimethylmaleic ahydride)-iron(II)hexafluoroantimonate [process a)]

3 g (3.907 mmol) of bis-(η⁶ -mesitylene)-iron(II) hexafluoroantimonateare melted with 7.6 g of freshly sublimed dimethylmaleic anhydride andthe mixture is degassed under argon. It is heated to 120° C. The eductdissolves slowly and a red solution is formed, which discolours toyellow after about 10 minutes and starts to crystallize out. The mixtureis cooled to room temperature. Dry toluene (50 ml) is added to the solidproduct and the excess anhydride is dissolved. After filtration under aninert gas and washing three times, the product is dried at roomtemperature under a high vacuum. 4.9 g (3.81 mmol=98% of theory) of ayellow crystalline, very hygroscopic product which becomes colourless inair due to uptake of water result.

Elemental analysis for C₃₆ H₃₆ O₁₈ FeSb₂ F₁₂

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       33.67  2.82;                                                Found:            30.77  3.34;                                                ______________________________________                                    

¹ H-NMR (DMSO): singlet at 1.98 ppm;

IR (KBr): very strong band at 660 cm⁻¹ ; the other bands largelycorrespond to those of dimethylmaleic anhydride; strong OH band at 3400cm⁻¹ due to uptake of H₂ O.

I.11. Preparation of hexa-(phthalatic anhydride)-iron(II)hexafluoroantimonate [process a)]

6 g (7.81 mmol) of bis-(η⁶ -mesitylene)-iron(II) hexafluoroantimonateare degassed in 25g of phthalic anhydride (distilled) and the mixture isheated to 130° C. under argon. After 1 hour at 130° C., the mixture iscooled to 100° C. and 150 ml of hot toluene are added. A yellowprecipitate forms and is filtered off hot under an inert gas and washedthree more times with hot dry toluene. After drying under a high vacuum,6.6 g of a yellow, hygroscopic crystalline product which becomescolourless in air result.

IR (KBr): strong band at 660 cm⁻¹ ; further bands at 3400, 1850, 1790,1630, 1600, 1260, 1110, 910 and 540 cm⁻¹ ;

¹ H-NMR (CDCl₃): signal at 7.95 ppm (multiplet, phthalic anhydride).

I.12. Preparation of hexa-(methylhexahydrophthalic anhydride)-iron(II)hexafluoroantimonate [process a)]

30.8 g (40.119 mmol) of bis-(η⁶ -mesitylene)-iron(II)hexafluoroantimonate are finely powdered, dried at 120° C. under a highvacuum for 2 hours and then added to 102.4 g of methylhexahydrophthalicanhydride, and the solution is degassed under argon and heated to 120°C. After about 20 minutes, everything has dissolved and the red colourhas disappeared. The mesitylene is then removed in vacuo (weight loss:9.7 g). A pale brownish 49.8% solution of the above compound in theanhydride, which can be isolated analogously to Example I.6., results.

IR (KBr): strong band at 660 cm⁻¹ ; the other bands largely correspondto those of the anhydride;

Elemental analysis for C₅₄ H₆₀ O₁₈ FeSb₂ F₁₂

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       42.21  4.72;                                                Found:            41.53  4.84.                                                ______________________________________                                    

I.13. Preparation of hexa-(caprolactone)-iron(II) hexafluoroantimonate[process a)]26 g (33.8 mmol) of bis-(η⁶ -mesitylene)-iron(II)hexafluoroantimonate are degassed in 50 ml of caprolactone under argonand the mixture is heated to 120° C. After 5 minutes, the red solutionbecomes colourless. After cooling to room temperature, the product iscrystallized out by addition of 400 ml of dry toluene. After filteringand washing (toluene) under an inert gas, the product is dried at roomtemperature under a high vacuum. 37.8 g (31.18 mmol=92% of theory) ofwhite, very hygroscopic crystals result.

Elemental analysis for C₃₆ H₆₀ O₁₂ FeSb₂ F₁₂ ;

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       35.67  4.99;                                                Found:            35.47  5.06;                                                ______________________________________                                    

IR (KBr): The IR spectrum is identical to that of the product which hasbeen prepared with UV light (I.1.).

The substance is identical with the compound prepared according to I.1.

I.14. Preparation of hexa-(tetrahydrofuran)-zinc(II)hexafluoroantimonate [process c)]10 ml (22 mmol) of zinc chlorideetherate in methylene chloride (2.2 mol) are added to 80 ml of drytetrahydrofuran (THF) and the mixture is degassed under argon and cooledto 0° C. in an ice bath. 12 g (35.4 mmol) of solid triethyloxoniumhexafluoroantimonate are added. The solids dissolved immediately andafter about 10 minutes the product starts to crystallize out. Thereaction mixture is heated to room temperature and after 4 hours theproduct is filtered off, washed three times with THF under an inert gasand dried under a high vacuum at room temperature. 16.3 g (16.8 mmol=95%of theory) of colourless, very hygroscopic crystals are obtained.

Elemental analysis for C₂₄ H₄₈ O₆ ZnSb₂ F₁₂ :

    ______________________________________                                                C      H      Zn        Sb   F                                        ______________________________________                                        Calculated:                                                                             29.73    4.99   6.74    25.12                                                                              23.52;                                 Found:    28.2     4.9    7.1     25.8 23.5;                                  ______________________________________                                    

¹ H-NMR (DMSO): signals at 3.95 ppm (2H, multiplet); 1.75 ppm (2H,multiplet);

IR (KBr): strong band at 660 cm⁻¹, further bands at 2860, 2980, 1460,1080 and 910 cm⁻¹ ; melting point: 180°-200° C. (decomposition).

I.15. Preparation of tris-(ethylene glycol dimethyl ether)-zinc(II)hexafluoroantimonate [process c)]

1 g (2.95 mmol) of triethyloxonium hexafluoroantimonate is dissolved in4 ml of dry ethylene glycol dimethyl ether. 0.6 ml (1.32 mmol) of zincchloride etherate in CH₂ Cl₂ (2.2 mol) is slowly added. After heating to40° C., the product starts to crystallize out. After filtration under aninert gas and washing three times with ethylene glycol dimethyl ether,the product is dried at room temperature under a high vacuum. 0.4 g (0.5mmol=33% of theory) of a colourless, crystalline, very hygroscopicproduct results.

Elemental analysis for C₁₂ H₃₀ O₆ ZnSb₂ F₁₂ :

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       17.85  3.74;                                                Found:            16.96  4.17;                                                ______________________________________                                    

¹ H-NMR (D₂ O): bands at 3.69 ppm (2H, singlet), 3.36 ppm (3H, singlet).

I.16. Preparation of (18-crown-6)-zinc(II) hexafluoroantimonate [processc)]

0.8 ml (1.76 mmol) of zinc chloride etherate in CH₂ Cl₂ (2.2 mol) isadded to 1 g of 18-crown-6, dissolved in 8 ml of CH₂ Cl₂. 10 g (2.9mmol) of triethyloxonium hexafluoroantimonate are added and the mixtureis left at room temperature. After about 30 minutes, the productcrystallizes out. After filtration, washing with methylene chloride anddrying under a high vacuum at room temperature, 0.6 g of colourlesscrystals which are stable in air is obtained.

¹ H-NMR (D₂ O): single at 3.67 ppm;

IR (KBr): strong band at 660 cm⁻¹ ; further bands at 3400, 3200, 2900,1470, 1350, 1260, 1100 (strong band), 950 and 820 cm⁻¹.

I.17. Preparation of tris-(ethylene glycol dimethyl ether)-iron(II)hexafluoroantimonate [process c)]

0.37 g (0.91 mmol) of FeCl₂ is dispersed in 10 ml of dry ethylene glycoldimethyl ether and the dispersion is degassed under argon. 2 g (5.9mmol) of triethyloxonium hexafluoroantimonate are added. After stirringat room temperature for 2 hours, the solution becomes dark and finecrystals form. After 4 hours, the product is filtered off under an inertgas, washed three times with ethylene glycol dimethyl ether and dried atroom temperature under a high vacuum. 20 g (2.51 mmol=86% of theory) ofa white, very hygroscopic crystalline compound result.

Elemental analysis for C₁₂ H₃₀ O₆ FeSb₂ F₁₂ :

    ______________________________________                                                        C    H                                                        ______________________________________                                        Calculated:       18.06  3.79;                                                Found:            17.70  4.02;                                                ______________________________________                                    

IR (KBr): strong band at 660 cm⁻¹ ; bands at 3400, 3000, 2900, 1460,1240 and 1050 cm⁻¹ ; ¹ H-NMR (D₂ O): singlet at 3.68 ppm (2H); 3.35 ppm(3H).

I.18. Preparation of bis-(ethylene glycol dimethyl ether)-manganese(II)hexafluoroantimonate [process c)]

0.33 g (2.62 mmol) of anhydrous MnCl₂ is suspended in 10 ml of dryethylene glycol dimethyl ether and the suspension is degassed underargon. 2.0 g (5.9 mmol) of triethyloxonium hexafluoroantimonate areadded and the mixture is stirred at room temperature. The MnCl₂dissolves and fine crystals are formed. After 4 hours, the violetsolution is filtered under an inert gas, washed three times withethylene glycol dimethyl ether and dried at room temperature under ahigh vacuum. 1.4 g of colourless crystals which deliquesce in air areobtained.

IR (KBr): strong band at 660 cm⁻¹ ; further bands at 2980, 2920, 1460,1100, 1060 and 880 cm⁻¹.

I.19. Preparation of hexa-(acetone)-iron(II) hexafluoroantimonate[process b)]

0.5 g (3.94 mmol) of FeCl₂ (anhydrous) is dispersed in 20 ml of acetoneand the mixture is degassed under argon. 2.70 g (7.88 mmol) of solidAgSbF₆ are added. AgCl is formed in a slightly exothermic reaction.After 30 minutes, the AgCl is filtered off under an inert gas and washedwith acetone. 1.1 g (7.72 mmol =98% of theory) AgCl result. The acetonesolution is concentrated in vacuo and the product is crystallized with30 ml of dry toluene.

2.35 g (7.68 mmol=68% of theory) of white, very hygroscopic crystals areobtained. ¹ H-NMR (D₂ O): signal at 2.08 ppm singlet;

IR (KBr): strong band at 660 cm⁻¹ ; further bands at 1700, 1420, 1380,1240 and 1050 cm⁻¹ ;

DSC: exothermic decomposition at 173° C.

I.20. Preparation of (acetone)-tin(II) hexafluoroantimonate [process b)]

Analogously to Example I.19, the above compound is isolated as ahygroscopic oil by reaction of stoichiometric amounts of SnCl₂ and2AgSbF₆.

I.21. Preparation of (tetrahydrofuran)-tin(II) hexafluoroantimonate[process d)]

1.58 g (7.29 mmol) of SbF₅ are degassed with argon and cooled to -78°C., and 5 ml of dry ethylene glycol dimethyl ether and 0.58 g (3.70mmol) of SnF₂ are carefully added. The mixture is slowly warmed to roomtemperature. After about 2 hours, all the SnF₂ has dissolved. 20 ml ofdry THF are added and the precipitate formed is rapidly filtered offunder an inert gas, rinsed with THF and dried under a high vacuum atroom temperature.

1.9 g of white, very hygroscopic crystals are obtained.

¹ H-NMR ((D₂ O): bands at 3.74 ppm (2H, multiplet), 1.87 ppm (2H,multiplet);

IR (KBr): strong band at 660 cm⁻¹ ; further bands at 3400, 2900, 2840,1620, 1420, 1240, 1110 and 860 cm⁻¹.

I.22. Preparation of (tetrahydrofuran)-(diacetone alcohol)-iron(II)hexafluoroantimonate [process d)]

0.68 g (1.291 mmol) of Fe(SbF₆)₂ is added to 5 ml of acetone underargon. The iron salt dissolves in an exothermic reaction and a darksolution forms. After filtration to remove traces of insoluble product,THF is added and the precipitate formed is filtered off under an inertgas and washed three times with THF. Drying under a high vacuum at roomtemperature gives 0.9 g of yellowish hygroscopic crystals.

IR (KBr): strong band at 660 cm⁻¹, further bands at 3440, 3000, 2880,1680, 1380, 1200, 1170, 1120 and 880 cm⁻¹,

¹ H-NMR (D₂ O): bands at 3.76 ppm (8H), 1.89 ppm (8H), 2.74 ppm (2H,singlet), 2.24 ppm (3H, singlet) and 1.27 ppm (6H, singlet), THF:diacetone alcohol=2:1.

I.23. Preparation of (polyethylene glycol)(acetone)-iron(II)hexafluoroantimonate [processes a)+e)]

2.5 g (3.25 mmol) of bis-(η⁶ -mesitylene)-iron(II) hexafluoroantimonateare dissolved in 10 ml of acetone, and 0.7 g of polyethylene glycol 200is added. After exposure analogously to Example I.2., the solutionbecomes completely bleached. After addition of toluene, the product isfiltered off under an inert gas, washed and dried under a high vacuum.2.5 g of a solid hygroscopic product results.

¹ H-NMR (D₂ O): bands at 3.93 ppm, 3.74 ppm and 2.23 ppm;acetone:polyethylene glycol about 1:1.

I.24. Preparation of (tetrahydrofuran)-aluminium(III)hexafluoroantimonate [process c)]

0.13 g (0.87 mmol) of aluminium trichloride is dissolved in 2 g of drydiethyl ether, and 5 ml of dry tetrahydrofuran are then added. 10 g(2.95 mmol) of solid triethyloxonium hexafluoroantimonate are added tothe clear solution under argon as an inert gas and dissolve immediately.After 5 minutes, the product starts to crystallize out. After 2 hours at40° C., the product is filtered off under an inert gas, washed twicewith dry THF and dried at room temperature under a high vacuum. 0.9 g offine colourless crystals is obtained.

¹ H-NMR (D₂ O): signals at 3.73 ppm (2H) and 1.78 ppm (2H);

IR (KBr): strong band at 660 cm⁻¹ ; further bands at 2880, 2900, 1450,1360, 1250, 1220, 1150 and 880 cm⁻¹ ;

DSC: peak at 175° C.+220° C. (exothermic decomposition).

I.25. Preparation of (acetone)-magnesium(II) hexafluoroantimonate[process b)]

Analogously to Example I.19., the abovementioned compound is isolated asa very hygroscopic, colourless product by reaction of MgCl₂ and AgSbF₆.

I.26. Preparation of (acetic acid)-iron(II) hexafluoroantimonate[process a)]

3.0 g (3.91 mmol) of bis-(η⁶ -mesitylene)-iron(II) hexafluoroantimonateare suspended in 25 ml of acetic acid and the suspension is degassedunder argon. The suspension is heated to 120° C. After 1 hour, all thesubstances have dissolved and the red colour has disappeared. The aceticacid is concentrated and the product is concentrated to dryness under ahigh vacuum at room temperature. 3.05 g of solid, hygroscopic beigeproduct are obtained.

¹ H-NMR (D₂ O): singlet at 2.09 ppm.

I.27. Preparation of (tetrahydrofuran)-iron(II) hexafluoroantimonate[process e)]

1.0 g of (acetic acid)-iron(II) hexafluoroantimonate are suspended in 10ml of THF and the suspension is refluxed for 5 minutes. After cooling toroom temperature, the product is filtered off under an inert gas andwashed with THF. 0.95 g of white, very hygroscopic product results.

¹ H-NMR (D₂ O): bands at 3.75 ppm (2H) and 1.89 ppm (2H).

II. Preparation of the initiator compositions according to the invention

Examples II.1. to II.3.

1 g of the complex according to Example I.9., I.4. or I.1. is dissolved,while heating (50° C./1 hour), in a solution consisting of 90 g ofmethylhexahydrophthalic anhydride and 10 g of a reaction product of twoequivalents of tetrahydrophthalic anhydride and one equivalent of2,2'-dimethylpropanediol.

Examples II.4. and II.5.

1 g of the complex according to Example I.1. or I.14 is dissolved in asolution consisting of 100 g of methylhexahydrophthalic anhydride whileheating (50° C./1 hour).

Example II.6.

The 49.8% solution of the complex according to Example I.12. is diluted100-fold with methylhexahydrophthalic anhydride.

Example II.7.

2 g of the complex according to Example I.9. are dissolved in 98 partsof diisocyanatodiphenylmethane, while heating (50° C./1 hour).

Example II.8.

2 g of the complex according to Example I.1. are dissolved in 98 partsof propylene carbonate.

Example II.9.

2 g of the complex according to Example I.1. are dissolved in 98 partsof caprolactone.

II.10. Preparation of an initiator solution containing(methylhexahydrophthalic anhydride)-tin(II)hexafluoroantimonate [processd)]

30 g of methylhexahydrophthalic anhydride are degassed at 120° C. underargon, and 1.02 g (6.50 mmol) of tin difluoride are added. Thesuspension is cooled in an ice bath and 2.80 g (12.92 mmol) of SbF₅ areslowly added in the course of 30 minutes. The mixture is warmed slowlyto room temperature and stirred for 12 hours. During this procedure, thetin difluoride dissolves almost completely. The solution is thenfiltered over a G-4 filter frit. Virtually no residue remains. Thisinitiator solution is diluted with methylhexahydrophthalic anhydride bya factor of 18.4.

II.11. Preparation of an initiator solution containing(methylhexahydrophthalic anhydride)-tin(II)hexafluoroantimonate fluoride[process d)]

Analogously to Example II.10., 3.70 g (2.36 mmol) of tin difluoride and5.08 g (2.34 mmol) of SbF₅ are reacted in 32 g ofmethylhexahydrophthalic anhydride. After filtration to remove traces ofinsoluble product, the solution is diluted with methylhexahydrophthalicanhydride by a factor of 27.4.

II.12. Preparation of an initiator solution containinghexa-(methylhexahydrophthalic anhydride)-iron(II) hexafluoroantimonate[process d)]

3.8 g of methylhexahydrophthalic anhydride are degassed at 100° C. andkept under argon. 5.8 mg (0.11 mmol) of Fe(SbF₆)₂ are dissolved in thiscompound at 40° C. The Fe(SbF₆)₂ is prepared in accordance with themethod of D. Gantar et al. J. Chem. Soc., Dalton Trans., 10, 2379-83(1978) by reaction of FeF₂ and SbF₅ in HF. The solution is filtered anddiluted 4.3-fold with methylhexahydrophthalic anhydride. A 1% solutionof the abovementioned complex results.

III. Use examples

Example III.1.

70 g of an industrial bisphenol A diglycidyl ether (epoxide value: 5.2equivalents/kg), 30 g of 3,4-epoxycyclohexylmethyl3',4'-epoxycyclohexanecarboxylate and 25 g of hardener componentsaccording to Examples II.1. to II.3. are mixed in an aluminium mould atroom temperature and the mixture is then heated at 200° C. for 1 hour.Solid shaped articles having the following glass transition temperatures(measured by the DSC method) result: T_(g) using the initiatorcomposition from Example II.1.: 181° C.;

T_(g) using the initiator composition from Example II.2.: 181° C.;

T_(g) using the initiator composition from Example II.3.: 179° C.

Example III.2.

100 g of an industrial bisphenol A diglycidyl ether (epoxide value: 5.2equivalents/kg) and 25 g of hardener components according to ExamplesII.4. to II.5. are mixed in an aluminium mould at room temperature andthe mixture is then heated at 200° C. for one hour. Solid shapedarticles having the following glass transition temperatures (measured bythe DSC method) result:

T_(g) using the initiator composition from Example II.4.: 156° C.;

T_(g) using the initiator composition from Example II.5.: 154° C.;

T_(g) using the initiator composition from Example II.6.: 164° C.;

Example III.3.

70 g of an industrial bisphenol A diglycidyl ether (epoxide value: 5.2equivalents/kg), 30 g of 3,4-epoxycyclohexylmethyl3',4'-epoxycyclohexanecarboxylate and 25 g of initiator componentaccording to Examples II.7.-II.9. are mixed at room temperature and themixture is then heated from 30° C. to 300° C. in a Mettler TA 3000 DSCapparatus. The heating-up rate is 10° C./minute. The T_(g) value isdetermined in the second DSC scan.

T_(g) using the initiator composition from Example II.7.: 192° C.;

T_(g) using the initiator composition from Example II.8.: 110° C.;

T_(g) using the initiator composition from Example II.9.: 107° C.;

Example III.4.

A 1% solution of the particular complex in methylhexahydrophthalicanhydride is prepared, or an initiator solution according to ExamplesII.10.-II.12. is used. One part of these initiator compositions is mixedwith 4 parts of a mixture of 70 g of an industrial bisphenol Adiglycidyl ether (epoxide value 5.2 equivalents/kg) and 30 g of3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate whilecooling with ice. This reactive mixture is heated from 30° C. to 300° C.in a Mettler TA 3000 DSC apparatus with a heating-up rate of 10°C./minute. The T_(g) value is then determined in a second DSC scan. Thegel time of the reactive mixture is determined at 120° C. and at 80° C.on a hotplate. The results are listed in the following table.

                  TABLE 1                                                         ______________________________________                                                    Gel                                                               Catalyst    time                  Exothermicity                               from Example                                                                              120°                                                                           80° C.                                                                         Tg    maximum                                     ______________________________________                                        I1          23"     47"     153° C.                                                                      105° C. + 145° C.             I2           7"     27"     155° C.                                                                      110° C. + 145° C.             I3          12"     35"     150° C.                                                                      140° C.                              I4          15"     43"     162° C.                                                                      135° C.                              I5           9"     35"     161° C.                                                                      140° C.                              I6          25"     50"     151° C.                                                                      145° C.                              I8          22"     50"     149° C.                                                                      145° C.                              I9          12"     29"     157° C.                                                                      139° C.                              I10         22"     48"     155° C.                                                                      110° C. + 140° C.             I11         22"     50"     159° C.                                                                      110° C. + 135° C.             I12         23"     48"     160° C.                                                                      140° C.                              I13         22"     45"     155° C.                                                                      105° C. + 140° C.             I14         17"     43"     168° C.                                                                      140° C.                              I15         18"     45"     165° C.                                                                      137° C.                              I16         22"     55"     163° C.                                                                      138° C.                              I17         11"     30"     148° C.                                                                      110° C. + 140° C.             I18         20"     80"     163° C.                                                                      135° C.                              I19         10"     37"     150° C.                                                                      145° C.                              I20         17"     47"     166° C.                                                                      142° C.                              I21         12"     65"     152° C.                                                                      150° C.                              II11        15"     95"     152° C.                                                                      108° C. + 145° C.             II10        15"     75"     154° C.                                                                      110° C. + 148° C.             II12        24"     120"    152° C.                                                                      110° C. + 150° C.             I22         23"     90"     157° C.                                                                      110° C. + 150° C.             I23         12"     35"     158° C.                                                                      100° C. + 145° C.             I24 (0.5% complex)                                                                        20"     90"     158° C.                                                                      180° C.                              I25         12"     50"     154° C.                                                                      142° C.                              I26         14"     55"     157° C.                                                                      100°  C. + 150° C.            ______________________________________                                    

What is claimed is:
 1. A compound of the formula II

    [(L.sup.1).sub.a M.sup.+n (L.sup.2).sub.b ].sup.n+ nX.sup.-(II)

in which n is 2 or 3, M is a metal cation selected from the groupconsisting of Zn²⁺, Mg²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cr²⁺, Ru²⁺, Mn²⁺, Sn²⁺,VO²⁺, Fe³⁺, Al³⁺ and Co³⁺, X⁻ is an anion which is selected from thegroup consisting of AsF₆ ⁻, SbF₆ ⁻, BiF₆ ⁻ and derivatives derived fromthese anions in which a fluorine atom is replaced by hydroxyl groups, orin which up to 50% of the anions X⁻, based on the total amount ofanions, can also be any desired anions, L¹ is a mono-to hexadentateσ-donor ligand and is an aliphatic, cycloaliphatic, aromatic oraraliphatic compound having one or two ketone, anhydride, carbonate orester groups or one to six ether groups per molecule, it being possiblefor the ligands L¹ of a compound of the formula II to differ in thecontext of the definitions given, L² is water, b is an integer from 0 to2, preferably 0, and, if L¹ is a monodentate ligand, a is an integerfrom 4 to 6 and the sum of a and b is in each case 6, and, if L¹ is abidentate ligand, a is an integer from 2 to 3 and the sum of 2a and b isin each case 6, and, if L¹ is a tridentate ligand, a is 2 and the sum of3a and b is 6, and if L¹ is a tetra-, penta- or hexadentate ligand, a is1 and the sum of 4a and b or of 5a and b is 6 and the sum of 6a and b is6 or 8, excluding bis{[12]-crown-4}-iron(II) hexafluoroantimonate, bis{[15]-crown-5}-iron(II) hexafluoroantimonate and ([12]-crown-4)([15]-crown5)-iron(II) hexafluoroantimonate.
 2. A compound of theformula II according to claim 1, in which a is 6 or 3, b is 0 and L¹ isan aliphatic, cycloaliphatic, aromatic or araliphatic compound havingone or two carboxylic acid anhydride groups.
 3. A process for thepreparation of a compound of the formula II

    [(L.sup.1).sub.a M.sup.+n (L.sup.2).sub.b ].sup.n+ nX.sup.-(II)

in which n is 2 or 3, M is a metal cation selected from the groupconsisting of Zn²⁺, Mg²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cr²⁺, Ru²⁺, Mn²⁺, Sn²⁺,VO²⁺, Fe³⁺, Al³⁺ and Co³⁺, X⁻ is an anion which is selected from thegroup consisting of AsF₆ ⁻, SbF₆ ⁻, BiF₆ ⁻ and derivatives derived fromthese anions in which a fluorine atom is replaced by hydroxyl groups, orin which up to 50% of the anions X⁻, based on the total amount ofanions, can also be any desired anions, L¹ is a mono- to hexadentateσ-donor ligand and is an aliphatic, cycloaliphatic, aromatic oraraliphatic compound having one or two ketone, anhydride, carbonate orester groups or one to six ether groups per molecule, it being possiblefor the ligands L¹ of a compound of the formula II to differ in thecontext of the definitions given, L² is water, b is an integer from 0 to2, preferably 0, and, if L¹ is a monodentate ligand, a is an integerfrom 4 to 6 and the sum of a and b is in each case 6, and, if L¹ is abidentate ligand, a is an integer from 2 to 3 and the sum of 2a and b isin each case 6 and, if L¹ is a tridentate ligand, a is 2 and the sum of3a and b is 6, and if L¹ is a tetra-, penta- or hexadentate ligand, a is1 and the sum of 4a and b or of 5a and b is 6 and the sum of 6a and b is6 or 8, which process comprises dissolving a compound of the formula IIa

    [(L.sup.3).sub.a M.sup.+n (L.sup.2).sub.b ].sup.n+ nX.sup.-(IIa)

in which M, L², X, n, a and b are as defined above and L³ is as definedfor L¹ above, together with an amount corresponding at least to thestoichiometry of the desired end product of a ligand L¹ which differsfrom L³, and heating the solution to carry out the ligand exchange.